clickhouse: configure backup directory. (#9277)

ClickHouse doesn't allow us to capture backups unless a backup directory
is configured, and we can't configure a backup directory without
restarting ClickHouse. To support backup collection for testing
purposes, and in case we wind up needing to use backups during
production operations, configure a ClickHouse backup directory via
clickhouse-admin.

Author: jmcarp

clickhouse-admin/types/src/config.rs

@@ -102,6 +102,7 @@ impl ReplicaConfig {
         let user_files_path = data_path.clone().join("user_files");
         let temp_files_path = data_path.clone().join("tmp");
         let format_schema_path = data_path.clone().join("format_schemas");
+        let backup_path = data_path.clone().join("backup");
         format!(
             "<!-- generation:{generation} -->
 <clickhouse>
@@ -204,9 +205,13 @@ impl ReplicaConfig {
 
         <!-- Controls how many tasks could be in the queue -->
         <max_tasks_in_queue>1000</max_tasks_in_queue>
-     </distributed_ddl>
+    </distributed_ddl>
 
-     <merge_tree>
+    <backups>
+        <allowed_path>{backup_path}</allowed_path>
+    </backups>
+
+    <merge_tree>
         <!-- Disable sparse column serialization, which we expect to not need -->
         <ratio_of_defaults_for_sparse_serialization>1.0</ratio_of_defaults_for_sparse_serialization>
 

clickhouse-admin/types/testutils/replica-server-config.xml

@@ -107,9 +107,13 @@
 
         <!-- Controls how many tasks could be in the queue -->
         <max_tasks_in_queue>1000</max_tasks_in_queue>
-     </distributed_ddl>
+    </distributed_ddl>
 
-     <merge_tree>
+    <backups>
+        <allowed_path>./data/backup</allowed_path>
+    </backups>
+
+    <merge_tree>
         <!-- Disable sparse column serialization, which we expect to not need -->
         <ratio_of_defaults_for_sparse_serialization>1.0</ratio_of_defaults_for_sparse_serialization>